Means for flowing wells



May 3, 1949. V o. EQDEMPSEY 2,469,225

' umus FOR FLowme WELLS Filed Feb, 4, 1946- s Sheets-Sheet 1 a rePatented May 3, 1949 UNITED STATES PATENT OFFICE MEANS FOR FLOWING WELLSOscar E. Dempsey, Tulsa, Okla., asslgnor to Dempsey Pump 00., Tulsa,Okla., a corporation Oklahoma Application February 4,1946, Serial No.645,305

11 Claims.

strata into a lower filling chamber and is displaced by input pressurefluid controlled through the operation of a valve mechanism in thelifting unit. The displacement operation is dependent upon overcoming adifferential pressur across a lower liquid discharge valve which ismoved relative to an outlet passageway for allowing discharge of fluidfrom the filling chamber to a reservoir located at a higher level.Movement of the liquid discharge valve is through the full length of itsstroke or travel which in turn will effect an operation of the valvecontrolling mechanism to close ofi the supply pressure fluid regardlessof whether all of the production fluid in th lower filling chamber isdisplaced or not. Furthermore, actuation of the valve mechanism by thedischarge valve to shut off supply of pressure fluid simultaneouslyprovides for the exhaust for all residue supply pressure fluid presentin the filling chamber and connecting passageways to eliminate anycounteracting pressure against the sand pressure of the productionfluid. This provides for a constant emission of fluid into the filingchamber except for the momentary interruption during the displacementoperation. 4

The present invention differs from applicant's co-pending applicationsupra in that the structure in the lower portion of the lifting unitcontrolling the discharge of the production fluid from a lower fillingchamber to the reservoir has been improved to assure a more positive andsubstant ally complete displacement of the productionfluid present inthe lower filling chamber prior to actuation of the valve controllingmechanism for closing off the motivating supply pressure fluid as wellas the bleeding ofi of the exhaust pressure.

It is, therefore, an important object of this invenion to provide alifting unit for the disp acement of fluid from a well whichprogressively lifts quantities-of the fluid from a lower collectionchamber to a reservoir disposed at a higher level, said lifting unithaving a valve mechanism for controlling the discharge of supplypressure fluid into the lower chamber wherein a portion of the displacedfluid acts as a snubber 5 to maintain said valve mechanism in an openposition for the discharge of the input pressure fluid untilsubstantially all of the production fluid from the lower chamber isdisplaced.

Still another object of this invention is to 10 provide a lifting unitfor displacing oil from a well by progressively lifting quantities offluid from the lower collection chamber to a reservoir disposed at ahigher level, said lifting unit having a valve mechanism controlling theinput of sup- 15 ply pressure fluid into the lower chamber fordisplacing the fluid as well as the exhausting of the residue supplypressure fluid after displacement of the fluid from the lower chamber.

And still another object of this invention is to provide a lifting unitfor displacing fluid from a well having an automatic valve mechanismcontrolling the discharge of supply pressure fluid into the well fordisplacing the well fluid and the exhaust of residue supply pressurfluid after displacement of the fluid, wherein the control mechanismprevents exhaust of supply pressure fluid during the displacement of thewell fluid and similarly prevents the supply pressure fluidfromdisplacing the well fluid during exhaust of residue supply fluidafter displacement.

Another object of this invention is to displace oil from a well in sucha manner to conserve the bottom hole pressure of the well in order tomaintain a substantially constant emission of well fluid from the sandstrata whereby oil can be continually emitted into the eduction tubingwithout regard to intervals of time.

And still another object of this invention is to bleed off residuesupply pressure fluid from a small section of the well depth from whichoil from the sand strata is displaced therefrom, said bleeding allowingexpeditious and repetitious flow of oil from the strata into saiddisplacement chamber, thereby eliminating considerable intervals of timewhich oil may be displaced.

And still another object of this invention is to allow escape offormation gas to the well surface at all times except a momentary periodwhen oil is being displaced or slugged to the top of the well.

And an additional object of this invention is the economic use of smallvolumes of gas in cubic feet fOr progressively lifting small amounts offluid into a reservoir to be intermittently slugged in predeterminedquantities, thereby eliminating the well bore.

the use of large volumes of gas to slug small amounts of entrapped oilall the way through the tubing string.

Other objects and advantages of the invention will be evident from thefollowing detailed description read in conjunction with the accompanyingdrawings which illustrate my invention.

In the drawings:

Fig. l is a fragmentary sectional view showing part of the lifting unitdisposed in a well bore.

Fig. 2 is an extension of Fig. 1 showing in elevation the lower portionof the lifting unit disposed in the well bore.

Fig. 3 is a fragmentary sectional elevational view shown schematicallyand slightly enlarged for clarity of the liftin unit disposed in thewell casing with the valve mechanism shown in one position beforedisplacement of the well fluid.

Fig. 4 is a view similar to Fig. 3 showing the position of the valvemechanismof the lifting unit h in a stage of operation.

Fig. is a similar view showing another position of the valve mechanismfor the lifting unit during the displacement of the well fluid.

Fig. 6 is a similar view to Fig. 5 showing the final position of thevalve mechanism for the lifting unit upon completing the operation ofdisplacing the well fluid.

Referring to the drawings in detail particularly Figs. 1 and 2 referencecharacter 2 represents a string of tubing disposed in spaced relation tothe well casing 3 extending to the sub-surface producing strata of thewell. A packing assembly 4 is connected to the tubing 2 by a collar 5,and comprises an outer cylindrical housing 6 having its outer peripheryprovided with a plurality of spaced annular packing glands 1. Below thepacking glands the housing 6 is provided with a pair of diametricallyopposed belly springs 8 having serrated slips 9 securing the assembly inthe well casing. The springs are secured to the housing 6 by welding orthe like. The cylindrical housing is provided with a longitudinal portIll providing communication with the chamber ll between the housing 6and easing 3 for the discharge of production and formation gas as willbe hereinafter explained. A ball check valve I2 is provided in the upperportion of passageway in for formation gas discharging therethrough tothe interior of the tubing 2. A string of tubing I3 is disposed in thehousing 6 in spaced relation thereto. Packing I4 is interposed betweenthe tubing [3 and inner periphery of housing 6.

A plurality of annular spaced apertures I5 provide communication betweena chamber l6 conpressure fluid into the lifting unit l8 as will behereinafter explained. The tubing I3 is connected by a collar I9 to alower tubing string of larger diameter extending downwardly and securedto a supportingmember 24 as will be hereinafter set forth. Extendingfrom the lowermost portion of housing 6 is an intermediate string oftubing 23 arranged in spaced relation between casing 3 and tubing 20.The tubing 23 extends downwardly from the housin 6 to the bottom ofposition is provided with an inwardly projecting ing shoulders 25adapted to cooperate with an outwardly projecting flange 26 provided inthe central portion of the cylindrical housing 22.

The tubing 23 at a predetermined Packing rings 21 surround the housing22 at the jointure of the tubings 20 and 23 with the member 24. Thelowermost end of the tubing 23 is provided with a perforated plug or gasanchor 28 for a purpose as will be hereinafter set forth. A cylindricaltubing 29 extends downwardly from the lowermost portion of the housing22. An apertured plug 36 is secured to the lower end of tubing 29 and isanchored in the gas anchor 28 by packing rings 3 I.

The upper portion of the housing 22 is provided with a plurality ofvertical bores 32 and '33 for receiving a differential valve unit 34 aswill be hereinafter set forth. The housing 22 is further provided with avalve bore 35 communicating with a chamber 36 which in turn communicateswith chamber 31. l The valve bores and chambers contain an automaticvalve mechanism similar to the valve mechanism disclosed in applicantscopending application heretofore-mentioned. The lowermost portion of thehousing 22 is provided with a bore 38 communicating with a lower chamber39 which houses a cylindrical piston having a main body portion orcircular flange 4| provided with oppositely extending cylinders 42 and43.

Referring now to the main valve unit 44 (Figs. 3 to 6, inclusively), aloosely disposed elongated valve 46 is disposed in the bore 35. Asubstantially cylindrical slide valve 41 is disposed in chamber 36.Wholly confined within the slide valve, and movable therein, is a pistonvalve 48. A pair of latch members 49 are loosely secured on studs 50anchored in the chamber 36. A valve locking pushrod 51 is disposed inthe chamber 36 immediately below the valve 46 and comprises an uppershaft 52 and a lower shaft 53. The rod 5! extends between the latchmembers 49 and into the interior of valves 41 and 48. A sleeve 54loosely surrounds the lower shaft 53 and is provided with a groove 55for a purpose as will be hereinafter set forth. The lower face of sleeve54 is provided with a shoulder 56 for anchoring one end of a helicalspring 51 having its opposite end resting on a surface 58 of valve 48.The valve 48 is provided with a transverse port 59 communicating withvertical ports 68 in .turn communicating with chamber 36. The outervalve 41 is provided with a port 6| and immediately below is a secondport 62 for a purpose as will be hereinafter explained. The uppercentral portion of the housing 22 is provided with a passageway 63communicating with an annulus 64 which in turn communicates with aplurality of circumferentially spaced apertures 65 providingcommunication with the inlet chamber II. In similar manner a verticalpassageway 66 communicates with an annulus 61 provided in housing 22,which in turn communicates with a plurality of circumferentially spacedapertures 68 communicating with the exhaust chamber i I.

From the foregoing, it will be apparent that the above-describedstructure is similar to that of applicants co-pending applicationheretofore-mentioned; however, the lower portion of the housing 22 isconstructed as to provide the piston unit 40 and complementary structureI tends in spaced relation through an aperture III 3 provided byinwardly projecting shoulders H of the cylinder 29 to'a position belowthe shoulders and into a chamber 12 provided in the lowermost portion ofcylinder 29. The lower end of cylinder 43 is provided with a cage 13 inwhich is disposed a ball check valve 14 cooperating with an aperture 15.The cylinder 29 is provided with a plurality of circumferentially spacedapertures 18. A second set of circumferentially spaced apertures 11 areprovided in the cylinder 29 in vertically spaced relationship toapertures 16. The plug 38 is provided with a ball check valve 19cooperating with an aperture 18.

The upper end of piston cylinder 42 is provided with a plurality ofapertures 88 for a purpose that willl be hereinafter explained. Apistonextension rod 8| comprising an upper shaft 82 and a lower shaft 83cooperates with piston cylinder 42. The lower shaft 83 extends through acentrally disposed aperture 88 of cylinder 42 and is provided with aprojection 83 of increased diameter confined within the interior ofpiston cylinder 42. The upper shaft 82 extends through an aperture 84provided by inwardly projecting shoulders 85 of housing 22. The shaft 82is provided with a circular flange 88 adapted to contact the shoulders85 and maintain the upper portion of shaft 82 in chambers 31 and 38. Theflange 4| is provided with a plurality of circular packing cups 88preventing leakage past the piston flange into the chamber 39.

It will be apparent that the sand pressure of the well will cause fluidfrom the production strata to flow through the plug 28, aperture 18,past valve 19, and through apertures 18 and 11, thereby filling chambers12 and 98 with production fluid. It will be apparent from Fig. 3 thatthe oil builds up in these filling chambers for displacement to areservoir located at a higher level.

Motive fluid pressure tained in the well from a surface compressor orlike equipment (not shown) into the chamber l6 and discharges into theinlet passageway I1, port 83, into constant communication with uppervalve units'34 and 44. Referring now to the valve unit 44, withproduction fluid standing in the lower filling chambers 12 and 98, Fig.3, it will be understood that production fluid is also present above thepiston flange 4| in chambers 39, bore 38, and the reservoir due to aprevious displacement operation of fluid from the lower filling chambersas will be more fully set out. The input motive pressure discharges fromport 83 into a bleed port 92 provided in main valve 48 and leaks betweenthe valve 48 and its bore into the chamber 38. It is to be understoodthat the fit of the valve 48 in its bore 35, especially the lowermostend of the valve below the horizontal leg portion of the bleed port 92,is such that the input pressure fluid discharging from port 92 isallowedto leak between the outer periphery of valve 48 and its bore intothe chamber 38. The small amount of pressure fluid constantly leakingthrough port 92 into the chamber 38 is not suflicient to warrant anydisplacement of liquid in the filling chambers 12 and 98. With themechanism of the lifting unit l8 in the position as shown in Fig. 3, theleakage pressure flowing into chamber 38 with the aid of tension spring51 will cause downward vertical movement of valve 48 until the port 59moves past the port 8|, thereby closing off the chamber 38 from exhaustpassageway 88. The downward movement of valve 48 contacts the base 93 ofvalve 41 and conis constantly maintinned leakage of supply pressurefluid into chamber 38 will build up the pressure therein, moving valve41 downward out of contact with the locking latches 49. The valve 41 isheld by friction and does not'move downward of its own weight during thepreliminary movement of valve 48. Furthermore, during the preliminarymovement of valve 48, the sleeve 54 is prevented from moving downward bythetension of spring 51. As s0on-as the top of valve 41 moves below theshoulders 94 of the locking latches 49, the latches are free to swingtransversely outward in the chamber 38 (Fig. 4), thereby releasing thelocking pushrod 5|. The rod 5| is then moved downward by valve 48actuated by input pressure fluid. Movement of valve 48 downwardly (Fig.4) opens passageway 95 to input pressure fluid which is directedtherethrough and into chamber 31 below the chamber 38.

A passageway 98 provides communication between chamber 31 and chamber 39at a position below the piston flange 4|. With the production fluiddisplaced by a previous operation to a position above the piston flange4| as shown in Fig. 4, discharge of input pressure fluid below theflange at a greater pressure than the static pressure of the productionfluid in chamber 39, bore 38, and reservoir 9| will move the piston 48vertically upward; however, upward movement of the piston is limited dueto a decrease in volume of oil in chamber 39, whereby the oil present inchamber 39 acts as a snubber to momentarily retard upward movement ofthe piston 4| and prevent actuation of the valve mechanism untilsubstantially all of the fluid is displaced from the filling chambers.With the snubbing action momentarily precluding further upward movementof the piston 48, the input pressure is then directed through port 18and outlets 16 into contact with the well fluid in the chambers 12 and98. As soon as the input pressure fluid increases sufliciently greaterthan the static pressure of the fluid in the filling chambers, it willcause displacement of the fluid from the chambers 12 and 98 through theball check valve 14 and into the interior of piston 48. The productionfluid being displaced through the interior of piston 48 dischargesthrough apertures 88, bore 38, outlet aperture 89, and into thereservoir 9|.

It will be apparent that simultaneous with the displacement of thefluidfrom the chambers 12 and 98, the input pressure fluid continues to actagainst the underface of piston flange 4|. With the production fluiddisplaced through piston 48, the input pressure fluid dischargingthrough annulus 18 also flows through the interior of piston 48,apertures 88 and into bore 38, causing a complete displacement of liquidinto the reservoir 9|.

The diameter of outlet aperture 89 is greater than the annulus 18 formedby the spaced relation of cylinder 43 and shoulder 1|, which providesfor,

a faster discharge of the input pressure fluid through the outletorifice 89 than the discharge thereof through the smaller annulus 18.This results in a decreased pressure condition in bore 38, allowing theoil in chamber 39 surrounding the piston cylinder 42 to be dischargedinto the annulus 99, bore 38, and the outlet 89. The annulus 99 isformed by the spaced relation of the cylinder 43 to the bore 38. Thedisplacement of fluid from chamber 39 above the piston is due to inputpressure fluid contacting the underface of piston flange 4| and it willbe apparent that the snubbing action of the fluid above the pistonflange and tubing 2 to the top of the well.

has been relieved, thereby causing the input pressure fluid to move thepiston 40 to completion of its upward stroke as shown in Fig. 6. Thefinal upward vertical movement of piston 40 causes the top portion ofpiston cylinder 43 to contact the larger shaft 02 of piston rod 8| (Fig.6), thereby moving the rod 8| upwardly through the apertured base 93to'causevertical upward movement of valve 48 and position ports 59 and60 into communication with port 8|, thereby exhausting the pressure inchamber 38 into passageway 68. Simultaneous with upward movement ofvalve 48, there is a vertical upward movement of pushrod causing theupper shaft 82 to move out of contact with the locking latches 49 sothey may swing transversely inward into the V-shaped groove 55 of sleeve54, at which time the rod shoulder 86 and supply fluid pressure inchamber 31 contacts the underface of valve base 93 to move valve 41vertically upward. The movement of rod 5| is assisted by tension spring51. Vertical upward movement of rod 52 causes movement of valve 46upward against the input pressure fluid to close of! the passageway 95.

In this position (Fig. 6), the locking latches 49 have been swunginwardly to lock the rod 5| and valve 46 in closed position. Themovement of the valve 41 vertically upward positions the port 52 intocommunication with exhaust passageway '68.

The residue input pressure fluid in passageways 95, 96, and chamber 31,as well as chambers I2 and 90, is allowed to exhaust through theapertured base 93, port 82, to the exhaust passageway 63, chamber II,passageway I0, valve I2, With the input pressure fluid cut off frompassageway 95 and the oil displaced from the chamber 90, it will beapparent that the production strata can flow through the apertured plug28 without interference from residue input pressure fluid. Furthermore,the static head of displaced fluid standing in reservoir 9| falls backthrough outlet port '89, bore 38, and this pressure with the assistanceof gravity moves the piston 40 vertically downward in chamber 39 to aposition shown in Fig. 3.

It will be understood that the relationship of pressures is commensuratewith the areas "with the various valves, pistons, and bores and theratio between them is a matter of choice dependent upon a particularwell. Furthermore, the length 'of tubing providing the reservoir 9| ismuch longer than the tubing for the filling chambers I2 and 90 in orderto provide a larger storage chamber or reservoir. In practice it hasbeen found that a ratio of 10 to l is satisfactory. It will also beunderstood that the formation gas from the production strata isliberated from 'the well through chamber II along with the exhaust orresidue supply pressurefluid exhausting through the passageway 65.

The upper portion of housing 22 is provided with the differential valveunit 34 which functions to allow discharge of supply pressure fluid intothe reservoir 9| for slugging the stored fluid onto the top of the wellas will now be fully explained. The valve unit 34 communicates with theinlet passageway 63 through a conduit I00 of valve I04 from passageway83 and simultaneously flowing through passageway I00 into bore '32 andport I03, it will be apparent there is an equal pressure on both sidesof valve I04 whereby a tension spring I05 maintains valve I04 in closedposition as shown in Fig. 4. A passageway I06 provides communicationbetween the reservoir 9| and the underface of valve I0'I.

With a sufficient increase in hydrostatic head in the reservoir 9|complementary with an increase in pressure beneath the valve IOIassisted by the tension spring I02, the constantly maintained supplypressure fluid acting against the top of valve IOI is overcome, causingthe valve to move vertically upward and close off port I03 and open aport III'I communicating between the port I03 and the underside of valveIOI. With the valve |0 in upward position, supply pressure fluid inchamber 33 is bled oil through the ports I03 and I01 into the chamber 32below the valve IOI, thereby unbalancing valve I04 by relieving pressureon one side thereof. With the unbalancing of valve I04, supply pressurefluid discharging from passageway 63 moves valve I04 upwardly to open aport I08, allowing discharge of supply pressure fluid directly into thereservoir 9| for displacing the fluid in the reservoir 9| upward to thetop of the well.,

As is clearly shown in Figures 1 and 2, the

housing in 22 is provided with a fishing neck IIO,

affording means for receivin any suitable hook and cable for lowering orlifting the lifting unit into and out of the well respectively. It willbe apparent that the unit I8 is of such size to easily pass through thetubings I3 and 2.

From the foregoing, it will be apparent that the invention contemplatesthe intermittent lifting of small quantities of oil from a lower fillingchamber to a higher reservoir, and functions in such manner to preventany supply pressure fluid utilized for displacing the oilfromcounteracting the sand pressure of the well, so that there is always aconstant emission of fluid from the production strata except for themomentary period during the displacement operation. Furthermore,thelifting unit comprises an automatic valve mechanism for controllingthe supply pressure fluid into the displacement chamber, and assuresthat substantially all of the production fluid is displaced from thefilling chamber prior to shutting ofl. the supply pressure fluid. This,is accomplished by utilizing a portion of the production fluid as asnubber against the supply pressure fluid in the displacement to exhaustall the residue supply pressure fluid and formation gas remaining fromthe displaceso that the supply pressure fluid is constantly ment of theproduction fluid in order to prevent a counteracting pressure againstthe sand pressure of the well. The lifting apparatus will operatesuccessfully in either deep or shallow wells, providing either high orlow sand pressure, and will displace the well fluid with a minimum ofsupply pressure fluid in the most economical and efficient manner.

Changes may be made in the combination and arrangement of parts asheretofore set forth in the specification and shown in the drawings, it

being understood that any modification in the precise embodiment of .theinvention may be made within the scope of the following claims withoutdeparting from the spirit of the invention.

What is claimed is: 1. In an apparatus for lifting fluid from a 9 wellincluding a filling chamber, means for introducing constantly maintainedmotive pressure fluid into the filling chamber for displacing the fluidemitting therein from the production strata, means for receiving thedisplaced fluid, means actuated by the motive pressure fluid to move thefirst mentioned means to a position preventing introduction of motivefluid into the filling chamber and permitting exhaust of residue motivefluid therefrom, said last mentioned means including a piston responsiveto previously displaced well fluid disposed above the piston to providea snubbing action to limit the actuation of the said means untilsubstantially all the production fluid in the filling chamber isdisplaced, and means independent of the first mentioned means andresponsive to the hydrostatic head of well fluid in the receiving meansfor introducing motive fluid thereto to slug the well fluid to the topof the well.

2. In an apparatus for lifting fluid from a Well comprising an automaticvalve unit communicating with an inlet passageway having a constantlymaintained motive pressure fluid therein, an accumulation chamber forwell fluid emitting irom the production strata, a reservoircommunicating with the valve unit and the accumulation chamber, a mainvalve in the unit and moveable by motive pressure fluid to open positionfor directing motive pressure fluid into the accumulation chamber fordisplacing well fluid therefrom, piston means operably connected withthe valve unit and moveable in response to motive pressure fluid toclose the main valve against motive pressure fluid after displacement ofthe well fluid from the accumulation chamber to the reservoir, saidpiston means having previously displaced well fluid standing on one sidethereof to snubber the movement of said piston means and prevent closingof the main valve until substantially complete displacement of the wellfluid from the accumulation chamber, and means independent of the mainvalve and responsive to the hydrostatic head of well fluid in thereservoir for introducing motive pressure fluid thereto to slug the wellfluid to the top of the well. a

3. In an apparatus for lifting fluid from a well having an eductiontubing and a well casing, said apparatus including a reservoircommunieating with the eduction tubing, a filling chamber communicatingwith the well casing and the reservoir, an automatic valve mechanismoperable in one position to direct constantly maintained motive pressurefluid from the casing into the filling chamber for displacing well fluidtherefrom, said mechanism operable in another position to bleed ofiresidue motive pressure fluid after displacement of well fluid from thefilling chamber, fluid means for snubbing the movement ot'the mechanismin the last mentioned position until substantially all the well fluid isdisplaced from the filling chamber, and means independent or the valvemechanism and responsive to the hydrostatic head of well fluid in thereservoir for introducing motive pressure fluid thereto to slug the wellfluid to the top of the well. I

4. In. an apparatus for fitting fluid from a well including a fillingchamber, a main valve mechanism controlling the introduction. ofconstantly maintained motive pressure fluid into the filling chamber fordisplacing the well fluid emitting therein from the production strata, areservoir well receiving the displaced fluid, a cylindrical pistonoperably connected with the valve mechanism and responsive to supplypressure fluid for actuating the valve mechanism to shut off the supplypressure fluid from the filling chamber after displacement of the wellfluid therefrom, said piston responsive to displaced well fluid standingabove the piston for limiting the movement of the piston in onedirection until substantially complete displacement of the well fluidfrom the filling chamber, and means independent of the main valve andresponsive to the hydrostatic head of well fluid in the reservoir forintroducing motive pressure fluid thereto to slug the well fluid to thetop of the well.

5. In an apparatus for lifting fluid from a well including a fillingchamber communicating with an eduction tubing, a main valve mechanismcommunicating with constantly maintained motive pressure fluid in theeduction tubing and moveable in response thereto for directing themotive pressure fluid into the filling chamber for displacing well fluidtherefrom, a cylindrical piston operably connected to the valvemechanism and responsive to the motive fluid pressure to move the valveto a position preventing introduction of motive fluid pressure into thefilling chamber, said piston cooperating with previously displaced wellfluid in the filling chamber and standing above the piston for retardingthe action of the motive pressure against the piston until substantiallyall the well fluid therein is displaced from the filling chamber, meansin the valve mechainsm permitting exhaust of residue supply pressurefluid after the displacement of well fluid from the filling chamber, andmeans independent of the main valve and responsive to the hydrostatichead of well fluid in the reservoir for introducing motive pressurefluid thereto to slug the well fluid to the top of the well.

6. In an apparatus for flowing wells including a filling chamber, aremovable lifting unit for introducing constantly maintained motivepressure fluid into the filling chamber for displacing oil emittingthereto from the production strata, a reservoir above the fillingchamber for receiving the displaced oil, said lifting unit comprising amain valve movable in one position to open a communicating passagewaydirecting motive fluid into the filling chamber, means in the liftingunit movable in response to the displacement of oil from the fillingchamber to allow .bleeding on of residue motive fluid therefrom, fluidmeans for snubbing the movement of the last mentioned means untilsubstantially all the well fluid is displacedfrom the filling chamber,and means independent of the valve means and responsive to thehydrostatic head of well fluid in the reservoir for introducing motivepressure fluid thereto to slug the well fluid to the top of the well.

7. In a lifting apparatus for lifting fluid from a well including afilling chamber and a reservoir, means for periodically introducingconstantly maintained motive pressure fluid into the filling chamber fordisplacing fluid emitting therein from the production strata to thereservoir, said means allowing bleeding oiT of residue motive fluidutilized in the displacement of the well fluid from the filling chamberand simultaneously preventing the introduction of motive pressure fluidduring the bleeding off of the residue motive fluid, and piston meanscooperating with previously displaced well fluid to snub the action ofsaid first mentioned means and prevent the bleeding off of the residuefluid until substantially all the production fluid in the filling llchamber is displaced therefrom, and means independent of the firstmentioned means and responsive to the hydrostatic of well fluid in thereservoir for introducing motive pressure fluid thereto to slug the wellfluid to the top of the well.

8. In a lifting apparatus for lifting fluid from a well including afilling chamber and a reservoir, means for periodically introducingconatantLv maintained motive pressure fluid into the filling chamber fordisplacing fluid emitting therein from the production strata to thereservoir, said means allowing bleeding of! of residue motive fluidutilized in the displacement of the well fluid from the filling chamberand simultaneously preventing the introduction of motive pressure fluidduring the bleeding 01f of the residue motive fluid, an apertured pistondisposed in the filling chamber and permitting discharge of the wellfluid therethrough, said piston having a flange co-operating withpreviously displaced well fluid standing thereabove for snubbing theaction of the first mentioned means for preventing bleed oil of theresidue pressure fluid "until substantially all the well ,fiuid in thefilling chamber is displaced therefrom.

9. In a lifting apparatus for lifting fluid from a well including 'afilling chamber and a reservoir. means for periodically introducingconstantly maintained motive pressure fluid into the filling chamber fordisplacing fluid emitting therein from the production strata to thereservoir, said means allowing bleeding off of residue motive'fluidutilized in the displacement of the wellfluid from the filling chamberand simultaneously preventing theintroduction of motive pressure fluidduring the bleeding of! of the residue motive fluid, an apertured pistondisposed in the filling chamber and permitting discharge of the wellfluid there-through, said piston having a flange co-operating withpreviously displaced well fluid standing thereabove for snubbing theaction of the first mentioned means for preventing bleed oil. of theresidue pressure fluid until substantially all of the well fluid in thefilling chamber is displaced therefrom, and means independent of thefirst mentioned means and responsive to the hydrostatic head of wellfluid in the reservoir for introducing motive pressure fluid thereto toslug the well fluid to the top of the well.

10. In a lifting apparatus for the intermittent lifting of fluid in awell to different stages of 12 elevation including a filling chamber anda hither reservoir chamber, means for directing constantly maintainedmotive pressure fluid into the filling chamber for displacing well fluidtherefrom, said means allowing bleeding oil of residue motive fluidutilized in the displacement of the well fluid from the fillingchamberand simultaneously preventing the introduction of motive pressure fluidduring the bleeding oil of the residue motive fluid, an apertured pistonoperably connected with the first mentioned means and having apassageway for discharge of the displaced fluid from the lower portionof the filling chamber to an upper portion of the filling chamber abovethe piston, said piston co-operating with displaced fluid standing abovethe piston for retarding the action of the first mentioned means andpreventing bleed off of the residue fluid until substantially all thewell fluid in the lower portion of the filling chamber is displacedtherefrom.

11. In a lifting apparatus for lifting fluid to difierent stages ofelevation in a well including a filling chamber and 'a higher'reservoircham-,

ber, means for directing supply pressure fluid into the filling chamberfor displacing well fluid therefrom, said means allowing bleeding oil ofresidue motive fluid utilized in the displacement of the well fluid fromthe filling chamber and simultaneously preventing ,the introduction ofmotive pressure fluid during the bleed oil of the residue fluid, controlmeans operably connected with the first mentioned means, means fordischarging the fluid from the filling chamber to a position above thecontrol means, said control means co-operating with the displaced fluidabove said control means for retarding the actuation of the firstmentioned means and preventing bleed ofi of the residue fluid untilsubstantially all the well fluid is displaced from the filling chamber.

OSCAR E. DEMPSEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Dempsey Mar. 5, 1946

